SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef897f789f74986e571792189d8d927635bdaeb35bcbd665ce464974824df536' 
  AND token = 'zPkXQxEljwRc1CBbjWEKyh+/U76tSsEMYdg53VWuTHo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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