All live stores (stores that have the domain set) have CDN out of the box.
The Cart plan does have CDN by default since it's intended for development purposes. That said, if you're testing WooCart for speed and would like to see the full performance, contact us and we'll configure it for you manually.
Some of your images might not load from a CDN
Our system tries to serve images as quickly as possible. In some cases, this means that it will load images concurrently from CDN and your store domain.