SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf344606d37915268a10306e4dcdafe13d9632c21bbc3ee531e99347606dc952' 
  AND token = 'nB9FwFnrXpvyqhXbrKFqGjUQ17ThRjvfjJyo7u+Mt6c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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