SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    3430, 3466, 3571, 3510, 3780, 3432, 3434, 
    3437, 3458, 3464, 3465, 9331, 3475, 
    3484, 3497, 3499, 3506, 3508, 3544, 
    3554, 9334, 3503, 9633, 3525, 9333, 
    3536, 3547, 3579, 3543, 3556, 3566, 
    3576, 3582, 3747, 9629, 3794, 3810, 
    3842, 9626, 3881, 3899, 3922, 3966, 
    4066, 4112, 4241, 4279, 3519, 4908, 
    3441, 3516, 4333, 5193, 3442, 3523, 
    3518, 4490, 3444, 5317, 3521, 3527, 
    4707, 3446, 3531, 5453, 3528, 6535, 
    3451, 5576, 3529, 6675, 5691, 3455, 
    6812, 3538, 5785, 6900, 5939, 7013, 
    6261, 7167, 9021, 6416
  )

Query time 0.00099

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "43.49"
    },
    "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": 106,
      "rows_produced_per_join": 106,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "22.29",
        "eval_cost": "21.20",
        "prefix_cost": "43.49",
        "data_read_per_join": "628K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`webmarco`.`cscart_categories`.`parent_id` in (3430,3466,3571,3510,3780,3432,3434,3437,3458,3464,3465,9331,3475,3484,3497,3499,3506,3508,3544,3554,9334,3503,9633,3525,9333,3536,3547,3579,3543,3556,3566,3576,3582,3747,9629,3794,3810,3842,9626,3881,3899,3922,3966,4066,4112,4241,4279,3519,4908,3441,3516,4333,5193,3442,3523,3518,4490,3444,5317,3521,3527,4707,3446,3531,5453,3528,6535,3451,5576,3529,6675,5691,3455,6812,3538,5785,6900,5939,7013,6261,7167,9021,6416))"
    }
  }
}