SELECT 
  category_id, 
  parent_id 
FROM 
  categories 
WHERE 
  parent_id IN(
    3893, 3888, 3899, 3885, 3892, 3903, 3896, 
    3897, 3898, 3895, 3902, 3884, 3891, 
    3889, 3890, 3904, 3901, 3886, 3894, 
    3900, 3887
  )

Query time 0.00064

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "4.84"
    },
    "table": {
      "table_name": "categories",
      "access_type": "range",
      "possible_keys": [
        "parent"
      ],
      "key": "parent",
      "used_key_parts": [
        "parent_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 21,
      "rows_produced_per_join": 21,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "2.74",
        "eval_cost": "2.10",
        "prefix_cost": "4.84",
        "data_read_per_join": "54K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`goimagine`.`categories`.`parent_id` in (3893,3888,3899,3885,3892,3903,3896,3897,3898,3895,3902,3884,3891,3889,3890,3904,3901,3886,3894,3900,3887))"
    }
  }
}