SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4f0fda57b470f18be35b49f8c3defd60778e5f809f12c0bbcc4eeac1acc98b9' 
  AND token = 'iI7STZaChitQtBbSFOxVb0PfrELD+/PS2P1cRZcpY/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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