SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    3039, 2655, 2645, 2658, 2663, 2662, 2657, 
    2666, 2660, 2642, 2653, 2650, 2664, 
    2652, 2667, 2668, 2648, 2656, 2641, 
    2913, 2659, 2661, 2665, 2644, 2647, 
    2651, 3094, 2643, 2640, 2646, 2649, 
    2654, 2215, 3093
  )

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "32.36"
    },
    "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": 53,
      "rows_produced_per_join": 53,
      "filtered": "100.00",
      "index_condition": "(`cscart_db`.`cscart_categories`.`parent_id` in (3039,2655,2645,2658,2663,2662,2657,2666,2660,2642,2653,2650,2664,2652,2667,2668,2648,2656,2641,2913,2659,2661,2665,2644,2647,2651,3094,2643,2640,2646,2649,2654,2215,3093))",
      "cost_info": {
        "read_cost": "27.06",
        "eval_cost": "5.30",
        "prefix_cost": "32.36",
        "data_read_per_join": "148K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ]
    }
  }
}