SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    235, 23, 22, 34, 29, 7, 8, 6, 10, 37, 18, 
    24, 9, 25, 28, 36, 50, 52, 33, 31, 389
  )

Query time 0.00047

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "20.11"
    },
    "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": 33,
      "rows_produced_per_join": 33,
      "filtered": "100.00",
      "index_condition": "(`test_uchur_k`.`cscart_categories`.`parent_id` in (235,23,22,34,29,7,8,6,10,37,18,24,9,25,28,36,50,52,33,31,389))",
      "cost_info": {
        "read_cost": "16.81",
        "eval_cost": "3.30",
        "prefix_cost": "20.11",
        "data_read_per_join": "174K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ]
    }
  }
}