SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26efa10d26176b02094ec54376329af9999bc05025440318baa375abf5e182c5' 
  AND token = 'BhW+oTL0lby42QeJxUUguOLKgOFejfUDag9xUlcrMfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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