SELECT 
  `name`, 
  `value` 
FROM 
  `cscart_addon_settings` 
WHERE 
  `addon` = 'seo'

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "0.90"
    },
    "table": {
      "table_name": "cscart_addon_settings",
      "access_type": "ref",
      "possible_keys": [
        "cscart_addons_settings_pk"
      ],
      "key": "cscart_addons_settings_pk",
      "used_key_parts": [
        "addon"
      ],
      "key_length": "767",
      "ref": [
        "const"
      ],
      "rows_examined_per_scan": 4,
      "rows_produced_per_join": 4,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "0.50",
        "eval_cost": "0.40",
        "prefix_cost": "0.90",
        "data_read_per_join": "6K"
      },
      "used_columns": [
        "addon",
        "name",
        "value"
      ]
    }
  }
}