SELECT 
  category_id, 
  parent_id 
FROM 
  ushop_categories 
WHERE 
  parent_id IN(318, 315, 316) 
  AND category_id != 264

Query time 0.00103

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "28.66"
    },
    "table": {
      "table_name": "ushop_categories",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "parent",
        "p_category_id"
      ],
      "key": "parent",
      "used_key_parts": [
        "parent_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 62,
      "rows_produced_per_join": 62,
      "filtered": "100.00",
      "index_condition": "(`marketplace`.`ushop_categories`.`parent_id` in (318,315,316))",
      "cost_info": {
        "read_cost": "22.46",
        "eval_cost": "6.20",
        "prefix_cost": "28.66",
        "data_read_per_join": "201K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`marketplace`.`ushop_categories`.`category_id` <> 264)"
    }
  }
}