SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    9339, 9581, 9499, 4276, 3341, 3768, 3356, 
    3515, 3541, 3727, 4356, 4545, 3522, 
    3777, 3363, 3346, 4287, 3785, 3380, 
    3463, 3530, 3387, 3467, 3788, 3410, 
    3471, 3555, 3797, 3428, 3481, 3801, 
    3436, 3489, 4041, 3443, 3495, 4061, 
    3500, 3449, 4081, 3457, 3537, 3565, 
    3575, 3584, 3589, 3592, 3723, 3729, 
    3733, 3740, 3749, 3757, 3762, 4118, 
    4162, 4182, 4208, 4230, 4248, 4263, 
    4297, 4309, 4488, 4526
  )

Query time 0.00063

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "36.27"
    },
    "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": 88,
      "rows_produced_per_join": 88,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "18.67",
        "eval_cost": "17.60",
        "prefix_cost": "36.27",
        "data_read_per_join": "521K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`webmarco`.`cscart_categories`.`parent_id` in (9339,9581,9499,4276,3341,3768,3356,3515,3541,3727,4356,4545,3522,3777,3363,3346,4287,3785,3380,3463,3530,3387,3467,3788,3410,3471,3555,3797,3428,3481,3801,3436,3489,4041,3443,3495,4061,3500,3449,4081,3457,3537,3565,3575,3584,3589,3592,3723,3729,3733,3740,3749,3757,3762,4118,4162,4182,4208,4230,4248,4263,4297,4309,4488,4526))"
    }
  }
}