SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6e83cc1f93611d7c5ac416b744793811b9ce6a01d617ece59f53604f1f331a4' 
  AND token = 'nvXQEjO5SYhJQHghOsX2wUpAymNVEkgzqZMPPspO5gU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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