SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    2744, 2745, 2746, 2747, 2748, 2749, 2754, 
    2760, 2755, 2756, 2750, 2751, 2757, 
    2752, 2753, 2759, 2758, 2761, 2762, 
    2763, 2764, 2765, 2926, 2919
  )

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "26.26"
    },
    "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": 45,
      "rows_produced_per_join": 45,
      "filtered": "100.00",
      "index_condition": "(`cscart_db`.`cscart_categories`.`parent_id` in (2744,2745,2746,2747,2748,2749,2754,2760,2755,2756,2750,2751,2757,2752,2753,2759,2758,2761,2762,2763,2764,2765,2926,2919))",
      "cost_info": {
        "read_cost": "21.76",
        "eval_cost": "4.50",
        "prefix_cost": "26.26",
        "data_read_per_join": "125K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ]
    }
  }
}