SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4661858a99d243301901ca7b173e60235fdc537a053d34ab192a571cd9d8fb8e' 
  AND token = 'cnRv6BJGulLsooDf676DjryPIet5jzheMDqEW0Nk5fU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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