SELECT 
  * 
FROM 
  cscart_ec_configuration_product 
WHERE 
  product_id = 23

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "2.41"
    },
    "table": {
      "table_name": "cscart_ec_configuration_product",
      "access_type": "ALL",
      "rows_examined_per_scan": 2,
      "rows_produced_per_join": 1,
      "filtered": "50.00",
      "cost_info": {
        "read_cost": "2.21",
        "eval_cost": "0.20",
        "prefix_cost": "2.41",
        "data_read_per_join": "56"
      },
      "used_columns": [
        "configuration_id",
        "status",
        "floor",
        "room_no",
        "product_id",
        "extra_information"
      ],
      "attached_condition": "(`atulecarter_new_april_setup`.`cscart_ec_configuration_product`.`product_id` = 23)"
    }
  }
}