SELECT 
  * 
FROM 
  cscart_products 
  LEFT JOIN cscart_products_categories ON cscart_products_categories.product_id = cscart_products.product_id 
  LEFT JOIN cscart_product_features_values ON cscart_product_features_values.product_id = cscart_products.product_id 
WHERE 
  cscart_products.company_id = 687 
  AND cscart_products_categories.category_id = 733

Query time 0.00195

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "364.84"
    },
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_products_categories",
          "access_type": "ref",
          "possible_keys": [
            "PRIMARY",
            "pt",
            "idx_pc_product_id_type"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "category_id"
          ],
          "key_length": "3",
          "ref": [
            "const"
          ],
          "rows_examined_per_scan": 399,
          "rows_produced_per_join": 399,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "0.55",
            "eval_cost": "39.90",
            "prefix_cost": "40.45",
            "data_read_per_join": "6K"
          },
          "used_columns": [
            "product_id",
            "category_id",
            "link_type",
            "position",
            "category_position"
          ],
          "attached_condition": "(`dev2`.`cscart_products_categories`.`product_id` is not null)"
        }
      },
      {
        "table": {
          "table_name": "cscart_products",
          "access_type": "eq_ref",
          "possible_keys": [
            "PRIMARY",
            "cscart_products_product_id_index"
          ],
          "key": "PRIMARY",
          "used_key_parts": [
            "product_id"
          ],
          "key_length": "3",
          "ref": [
            "dev2.cscart_products_categories.product_id"
          ],
          "rows_examined_per_scan": 1,
          "rows_produced_per_join": 39,
          "filtered": "10.00",
          "cost_info": {
            "read_cost": "99.75",
            "eval_cost": "3.99",
            "prefix_cost": "180.10",
            "data_read_per_join": "300K"
          },
          "used_columns": [
            "product_id",
            "product_code",
            "product_type",
            "status",
            "company_id",
            "amount",
            "weight",
            "length",
            "width",
            "height",
            "shipping_freight",
            "low_avail_limit",
            "timestamp",
            "updated_timestamp",
            "usergroup_ids",
            "is_edp",
            "is_ship",
            "edp_shipping",
            "unlimited_download",
            "tracking",
            "free_shipping",
            "zero_price_action",
            "is_pbp",
            "is_op",
            "is_oper",
            "is_returnable",
            "return_period",
            "avail_since",
            "out_of_stock_actions",
            "localization",
            "min_qty",
            "max_qty",
            "qty_step",
            "list_qty_count",
            "tax_ids",
            "age_verification",
            "age_limit",
            "options_type",
            "exceptions_type",
            "details_layout",
            "shipping_params",
            "parent_product_id",
            "yml2_brand",
            "yml2_origin_country",
            "yml2_store",
            "yml2_pickup",
            "yml2_delivery",
            "yml2_adult",
            "yml2_delivery_options",
            "yml2_bid",
            "yml2_model",
            "yml2_sales_notes",
            "yml2_type_prefix",
            "yml2_offer_type",
            "yml2_market_category",
            "yml2_manufacturer_warranty",
            "yml2_expiry",
            "yml2_purchase_price",
            "yml2_description",
            "yml2_cpa",
            "ab__stickers_manual_ids",
            "ab__stickers_generated_ids",
            "source_import_key",
            "external_id",
            "update_1c",
            "sort_index",
            "guarantee_id",
            "conditions",
            "year",
            "city_place",
            "place_end_date",
            "number_purchases",
            "guarantees_crm",
            "extent",
            "pack",
            "pack_amount",
            "pack_logic",
            "city_id",
            "region_id",
            "individual_meta_data",
            "brand_id",
            "real_company_id",
            "is_send_to_telegram",
            "moderation_product_id",
            "is_cloned_for_moderation",
            "last_update_user_id",
            "uniqueSale",
            "is_confiscated",
            "type_of_sale"
          ],
          "attached_condition": "(`dev2`.`cscart_products`.`company_id` = 687)"
        }
      },
      {
        "table": {
          "table_name": "cscart_product_features_values",
          "access_type": "ref",
          "possible_keys": [
            "product_id",
            "idx_product_feature_variant_id"
          ],
          "key": "product_id",
          "used_key_parts": [
            "product_id"
          ],
          "key_length": "3",
          "ref": [
            "dev2.cscart_products_categories.product_id"
          ],
          "rows_examined_per_scan": 6,
          "rows_produced_per_join": 244,
          "filtered": "100.00",
          "cost_info": {
            "read_cost": "160.31",
            "eval_cost": "24.43",
            "prefix_cost": "364.84",
            "data_read_per_join": "188K"
          },
          "used_columns": [
            "feature_id",
            "product_id",
            "variant_id",
            "value",
            "value_int",
            "lang_code"
          ]
        }
      }
    ]
  }
}