SELECT 
  category_id 
FROM 
  cscart_categories 
WHERE 
  id_path LIKE '260/%'

Query time 0.00037

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE cscart_categories range id_path,idx_id_path id_path 767 9 Using index condition

Result

category_id
265
385
266
374
375
376
377
378
379
380
381
382
398
399
400
401