SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cc979f43136a616ffce819206c4c81664aca61306926b07fb76c7a466a6ac27d' 
  AND token = 'QknxdEldgQVGxAjLS14mjCxTV38XM+gnHko+TWTMdFU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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