SELECT 
  category_id 
FROM 
  cscart_categories 
WHERE 
  id_path LIKE '265/280/291/%'

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_categories",
      "access_type": "range",
      "possible_keys": ["id_path"],
      "key": "id_path",
      "key_length": "767",
      "used_key_parts": ["id_path"],
      "rows": 19,
      "filtered": 100,
      "index_condition": "cscart_categories.id_path like '265/280/291/%'"
    }
  }
}

Result

category_id
1618
1644
1645
1647
1650
1652
1654
1655
1660
1662
1663
1671
1672
1679
1680
1682
1683
1684
313