SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    23766, 23504, 23728, 23502, 23501, 23664, 
    23663, 23500, 23775, 23503, 23499, 
    23505
  )

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "3.66"
    },
    "table": {
      "table_name": "cscart_categories",
      "access_type": "range",
      "possible_keys": [
        "parent"
      ],
      "key": "parent",
      "used_key_parts": [
        "parent_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 17,
      "rows_produced_per_join": 17,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "1.96",
        "eval_cost": "1.70",
        "prefix_cost": "3.66",
        "data_read_per_join": "44K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`maniamall_cscart`.`cscart_categories`.`parent_id` in (23766,23504,23728,23502,23501,23664,23663,23500,23775,23503,23499,23505))"
    }
  }
}

Result