SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    36809, 36827, 36808, 36799, 36805, 36800, 
    36862, 36797, 36798, 36842, 36865, 
    36864
  )

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "4.13"
    },
    "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": 16,
      "rows_produced_per_join": 16,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "2.53",
        "eval_cost": "1.60",
        "prefix_cost": "4.13",
        "data_read_per_join": "41K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`maniamall_cscart`.`cscart_categories`.`parent_id` in (36809,36827,36808,36799,36805,36800,36862,36797,36798,36842,36865,36864))"
    }
  }
}

Result