SELECT 
  category_id, 
  parent_id 
FROM 
  categories 
WHERE 
  parent_id IN(
    6524, 12571, 12570, 5958, 6624, 5913, 
    18672, 6530, 18743, 5908, 5909, 5947, 
    6540, 6539, 5949, 5906, 5937, 5942, 
    5939, 6532, 5907, 6001, 6528, 5954, 
    5955, 5948, 5957, 14879, 6531, 5960, 
    5950, 5953, 18671, 18742, 5938, 5946, 
    8960, 15564, 6472, 6006, 6141, 2843, 
    18670, 6004, 18669, 18673, 5945, 5952, 
    11490, 11489, 5969, 5941, 5940, 6473, 
    5910, 5956, 11760, 6007, 6011, 11379, 
    6526, 5943, 6527, 6033, 6533, 6018, 
    5972, 6020, 6525, 6017
  )

Query time 0.00111

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "24.29"
    },
    "table": {
      "table_name": "categories",
      "access_type": "range",
      "possible_keys": [
        "parent"
      ],
      "key": "parent",
      "used_key_parts": [
        "parent_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 118,
      "rows_produced_per_join": 118,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "12.49",
        "eval_cost": "11.80",
        "prefix_cost": "24.29",
        "data_read_per_join": "308K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`goimagine`.`categories`.`parent_id` in (6524,12571,12570,5958,6624,5913,18672,6530,18743,5908,5909,5947,6540,6539,5949,5906,5937,5942,5939,6532,5907,6001,6528,5954,5955,5948,5957,14879,6531,5960,5950,5953,18671,18742,5938,5946,8960,15564,6472,6006,6141,2843,18670,6004,18669,18673,5945,5952,11490,11489,5969,5941,5940,6473,5910,5956,11760,6007,6011,11379,6526,5943,6527,6033,6533,6018,5972,6020,6525,6017))"
    }
  }
}