SELECT 
  field_id 
FROM 
  ushop_profile_fields 
WHERE 
  1 
  AND section = "C" 
  AND profile_show = "Y" 
  AND profile_required = "Y" 
  AND field_name = "phone"

Query time 0.00048

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "3.50"
    },
    "table": {
      "table_name": "ushop_profile_fields",
      "access_type": "ref",
      "possible_keys": [
        "field_name",
        "profile_show"
      ],
      "key": "field_name",
      "used_key_parts": [
        "field_name"
      ],
      "key_length": "98",
      "ref": [
        "const"
      ],
      "rows_examined_per_scan": 10,
      "rows_produced_per_join": 0,
      "filtered": "0.62",
      "cost_info": {
        "read_cost": "2.50",
        "eval_cost": "0.01",
        "prefix_cost": "3.50",
        "data_read_per_join": "66"
      },
      "used_columns": [
        "field_id",
        "field_name",
        "profile_show",
        "profile_required",
        "section"
      ],
      "attached_condition": "((`marketplace`.`ushop_profile_fields`.`section` = 'C') and (`marketplace`.`ushop_profile_fields`.`profile_show` = 'Y') and (`marketplace`.`ushop_profile_fields`.`profile_required` = 'Y'))"
    }
  }
}