SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08cfb8818a7e497617cad3c63206a9a7a3d1ed379fcf92ac2d9f7874603e068f' 
  AND token = 'a91hOzFWF7LcOyACGVL37NDw1xz1o05uPcKSbaiMf4g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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