SELECT 
  v.feature_id, 
  v.value, 
  v.value_int, 
  v.variant_id, 
  f.feature_type, 
  fd.internal_name, 
  fd.description, 
  fd.prefix, 
  fd.suffix, 
  vd.variant, 
  f.parent_id, 
  f.position, 
  gf.position as gposition, 
  f.display_on_header, 
  f.display_on_catalog, 
  f.display_on_product, 
  f.feature_code, 
  f.purpose 
FROM 
  cscart_product_features as f 
  LEFT JOIN cscart_product_features_values as v ON v.feature_id = f.feature_id 
  LEFT JOIN cscart_product_features_descriptions as fd ON fd.feature_id = v.feature_id 
  AND fd.lang_code = 'ru' 
  LEFT JOIN cscart_product_feature_variants fv ON fv.variant_id = v.variant_id 
  LEFT JOIN cscart_product_feature_variant_descriptions as vd ON vd.variant_id = fv.variant_id 
  AND vd.lang_code = 'ru' 
  LEFT JOIN cscart_product_features as gf ON gf.feature_id = f.parent_id 
  AND gf.feature_type = 'G' 
WHERE 
  f.status IN ('A') 
  AND v.product_id = 26421 
  AND f.display_on_catalog = 'Y' 
  AND (
    f.categories_path = '' 
    OR FIND_IN_SET(558, f.categories_path) 
    OR FIND_IN_SET(712, f.categories_path)
  ) 
  AND IF(
    f.parent_id, 
    (
      SELECT 
        status 
      FROM 
        cscart_product_features as df 
      WHERE 
        df.feature_id = f.parent_id
    ), 
    'A'
  ) IN ('A') 
  AND (
    v.variant_id != 0 
    OR (
      f.feature_type != 'C' 
      AND v.value != ''
    ) 
    OR (f.feature_type = 'C') 
    OR v.value_int != ''
  ) 
  AND v.lang_code = 'ru' 
ORDER BY 
  fd.internal_name, 
  fv.position

Query time 0.00089

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "0.97"
    },
    "ordering_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "nested_loop": [
        {
          "table": {
            "table_name": "v",
            "access_type": "ref",
            "possible_keys": [
              "PRIMARY",
              "fl",
              "variant_id",
              "lang_code",
              "product_id",
              "fpl",
              "idx_product_feature_variant_id"
            ],
            "key": "product_id",
            "used_key_parts": [
              "product_id"
            ],
            "key_length": "3",
            "ref": [
              "const"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 0,
            "filtered": "50.00",
            "index_condition": "((`dev2`.`v`.`lang_code` = 'ru') and (`dev2`.`v`.`feature_id` is not null))",
            "cost_info": {
              "read_cost": "0.64",
              "eval_cost": "0.05",
              "prefix_cost": "0.74",
              "data_read_per_join": "395"
            },
            "used_columns": [
              "feature_id",
              "product_id",
              "variant_id",
              "value",
              "value_int",
              "lang_code"
            ]
          }
        },
        {
          "table": {
            "table_name": "f",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "status"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "feature_id"
            ],
            "key_length": "3",
            "ref": [
              "dev2.v.feature_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 0,
            "filtered": "8.05",
            "cost_info": {
              "read_cost": "0.12",
              "eval_cost": "0.00",
              "prefix_cost": "0.91",
              "data_read_per_join": "64"
            },
            "used_columns": [
              "feature_id",
              "feature_code",
              "purpose",
              "feature_type",
              "categories_path",
              "parent_id",
              "display_on_product",
              "display_on_catalog",
              "display_on_header",
              "status",
              "position"
            ],
            "attached_condition": "((`dev2`.`f`.`status` = 'A') and (`dev2`.`f`.`display_on_catalog` = 'Y') and ((`dev2`.`f`.`categories_path` = '') or (0 <> find_in_set(558,`dev2`.`f`.`categories_path`)) or (0 <> find_in_set(712,`dev2`.`f`.`categories_path`))) and (if(`dev2`.`f`.`parent_id`,(/* select#2 */ select `dev2`.`df`.`status` from `dev2`.`cscart_product_features` `df` where (`dev2`.`df`.`feature_id` = `dev2`.`f`.`parent_id`)),'A') = 'A') and ((`dev2`.`v`.`variant_id` <> 0) or ((`dev2`.`f`.`feature_type` <> 'C') and (`dev2`.`v`.`value` <> '')) or (`dev2`.`f`.`feature_type` = 'C') or (`dev2`.`v`.`value_int` <> 0)))",
            "attached_subqueries": [
              {
                "dependent": true,
                "cacheable": false,
                "query_block": {
                  "select_id": 2,
                  "cost_info": {
                    "query_cost": "0.35"
                  },
                  "table": {
                    "table_name": "df",
                    "access_type": "eq_ref",
                    "possible_keys": [
                      "PRIMARY"
                    ],
                    "key": "PRIMARY",
                    "used_key_parts": [
                      "feature_id"
                    ],
                    "key_length": "3",
                    "ref": [
                      "dev2.f.parent_id"
                    ],
                    "rows_examined_per_scan": 1,
                    "rows_produced_per_join": 1,
                    "filtered": "100.00",
                    "cost_info": {
                      "read_cost": "0.25",
                      "eval_cost": "0.10",
                      "prefix_cost": "0.35",
                      "data_read_per_join": "1K"
                    },
                    "used_columns": [
                      "feature_id",
                      "status"
                    ]
                  }
                }
              }
            ]
          }
        },
        {
          "table": {
            "table_name": "fd",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "feature_id",
              "lang_code"
            ],
            "key_length": "9",
            "ref": [
              "dev2.v.feature_id",
              "const"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 0,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "0.01",
              "eval_cost": "0.00",
              "prefix_cost": "0.92",
              "data_read_per_join": "113"
            },
            "used_columns": [
              "feature_id",
              "description",
              "internal_name",
              "prefix",
              "suffix",
              "lang_code"
            ]
          }
        },
        {
          "table": {
            "table_name": "fv",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "variant_id"
            ],
            "key_length": "3",
            "ref": [
              "dev2.v.variant_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 0,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "0.01",
              "eval_cost": "0.00",
              "prefix_cost": "0.94",
              "data_read_per_join": "62"
            },
            "used_columns": [
              "variant_id",
              "position"
            ]
          }
        },
        {
          "table": {
            "table_name": "vd",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "variant_id",
              "lang_code"
            ],
            "key_length": "9",
            "ref": [
              "dev2.fv.variant_id",
              "const"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 0,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "0.01",
              "eval_cost": "0.00",
              "prefix_cost": "0.95",
              "data_read_per_join": "174"
            },
            "used_columns": [
              "variant_id",
              "variant",
              "lang_code"
            ]
          }
        },
        {
          "table": {
            "table_name": "gf",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "feature_id"
            ],
            "key_length": "3",
            "ref": [
              "dev2.f.parent_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 0,
            "filtered": "100.00",
            "cost_info": {
              "read_cost": "0.01",
              "eval_cost": "0.00",
              "prefix_cost": "0.97",
              "data_read_per_join": "64"
            },
            "used_columns": [
              "feature_id",
              "feature_type",
              "position"
            ],
            "attached_condition": "<if>(is_not_null_compl(gf), (`dev2`.`gf`.`feature_type` = 'G'), true)"
          }
        }
      ]
    }
  }
}