SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ad346bd934d091e6990912074502da9d9bb2d856a1dbef4003469f4fb5f878d' 
  AND token = 'Cpe4CLqfQqjCYnpsaKhOCEDjmMThY4HP0hUH9JPYkZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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