SELECT 
  * 
FROM 
  cscart_wk_delivery_day_settings 
WHERE 
  company_id = 16 
  AND shipping_id = 13 
  AND day_disabled = 'N'

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "0.35"
    },
    "table": {
      "table_name": "cscart_wk_delivery_day_settings",
      "access_type": "ref",
      "possible_keys": [
        "shipping_id"
      ],
      "key": "shipping_id",
      "used_key_parts": [
        "shipping_id"
      ],
      "key_length": "3",
      "ref": [
        "const"
      ],
      "rows_examined_per_scan": 1,
      "rows_produced_per_join": 0,
      "filtered": "5.00",
      "cost_info": {
        "read_cost": "0.25",
        "eval_cost": "0.01",
        "prefix_cost": "0.35",
        "data_read_per_join": "1"
      },
      "used_columns": [
        "delivery_day_setting_id",
        "shipping_id",
        "dispatch_to_courier",
        "day_disabled",
        "weekday_id",
        "company_id"
      ],
      "attached_condition": "((`wearethehelpful_scalesta_net`.`cscart_wk_delivery_day_settings`.`company_id` = 16) and (`wearethehelpful_scalesta_net`.`cscart_wk_delivery_day_settings`.`day_disabled` = 'N'))"
    }
  }
}