SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afee755a718fa48be34384454c1939cb3fbb60c57f6997a96cdbde5415821a56' 
  AND token = '3FC9uS/WVz9xPBjn6LrdJzXO2KmMU+EP1EdNnr51IZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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