SELECT 
  category_id 
FROM 
  cscart_categories 
WHERE 
  id_path LIKE '2/%'

Query time 0.00065

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "22.31"
    },
    "table": {
      "table_name": "cscart_categories",
      "access_type": "range",
      "possible_keys": [
        "id_path"
      ],
      "key": "id_path",
      "used_key_parts": [
        "id_path"
      ],
      "key_length": "767",
      "rows_examined_per_scan": 49,
      "rows_produced_per_join": 49,
      "filtered": "100.00",
      "index_condition": "(`test_uchur_k`.`cscart_categories`.`id_path` like '2/%')",
      "cost_info": {
        "read_cost": "17.41",
        "eval_cost": "4.90",
        "prefix_cost": "22.31",
        "data_read_per_join": "259K"
      },
      "used_columns": [
        "category_id",
        "id_path"
      ]
    }
  }
}

Result

category_id
118
119
223
224
232
125
126
362
363
364
365
366
367
378
150
319
154
225
322
342
355
132
134
217
231
250
296
133
172
176
184
185
186
193
270
204
21
233
261
3
117
158
183
190
191
192
205
248
258
281
35
359
4
308
315
318
38
199
227
237
333
334
79
80
81
39
395
77
285
78
82
167
168
170
171
201
262
290
313
259
260
275
279
303
326
368
83
84
299
339
361
85