SELECT 
  category_id, 
  parent_id 
FROM 
  categories 
WHERE 
  parent_id IN(
    7651, 240, 7581, 271, 11179, 195, 236, 
    45, 221, 244, 22751, 250, 183, 228, 189, 
    257, 268, 216, 209, 272, 229, 222, 251, 
    217, 269, 46, 245, 258, 196, 210, 237, 
    184, 100, 76, 218, 259, 252, 185, 211, 
    270, 230, 238, 197, 273, 52, 47, 212, 
    219, 198, 247, 224, 274, 48, 231, 260, 
    253, 186, 220, 254, 261, 187, 213, 22775, 
    199, 255, 188, 200, 50, 226, 241, 262, 
    214, 190, 242, 256, 279, 215, 51, 234, 
    227, 201, 263, 277, 99, 191, 202, 264, 
    6637, 235, 192, 203, 6635, 6638, 278, 
    265, 204, 125, 6636, 266, 6667, 193, 
    267, 194, 205, 179, 275, 206, 6634, 6639, 
    207, 208, 7580, 6640, 6641, 6644, 7582
  )

Query time 0.00145

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "51.35"
    },
    "table": {
      "table_name": "categories",
      "access_type": "range",
      "possible_keys": [
        "parent"
      ],
      "key": "parent",
      "used_key_parts": [
        "parent_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 253,
      "rows_produced_per_join": 253,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "26.05",
        "eval_cost": "25.30",
        "prefix_cost": "51.35",
        "data_read_per_join": "662K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`goimagine`.`categories`.`parent_id` in (7651,240,7581,271,11179,195,236,45,221,244,22751,250,183,228,189,257,268,216,209,272,229,222,251,217,269,46,245,258,196,210,237,184,100,76,218,259,252,185,211,270,230,238,197,273,52,47,212,219,198,247,224,274,48,231,260,253,186,220,254,261,187,213,22775,199,255,188,200,50,226,241,262,214,190,242,256,279,215,51,234,227,201,263,277,99,191,202,264,6637,235,192,203,6635,6638,278,265,204,125,6636,266,6667,193,267,194,205,179,275,206,6634,6639,207,208,7580,6640,6641,6644,7582))"
    }
  }
}