SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '394dad00724739de62988f41c8d041de3a664acaaeb301445895c3b81dda1743' 
  AND token = 'N9x1hqWpUzEOySKkaLujYWD82xZzYsgwncLHdARe8tU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}