SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7a0c059e374fd851acf6741a9566f1792cedae30d5ffc424a53354c9d991b50' 
  AND token = 'DCbmT88POXXDQKRtKnGKVQ93UZDt3cFDlwOTfNOWCXU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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