Go to 'Orders' and fill in the 2 Quick Search fields. Scroll down to find the order. When you see a green tick mark in the column Considered Safe, the order has been paid. You can also click on the order line to find the green tick mark next to Considered Safe.
You can find the order in the back office via Reports -> Payment Cluster Details. Enter one of the 3 IDs and click Search. On the left hand side you will see the Payment cluster state. If the status is paid or closed_success, the order has been paid by the customer. Paid means that the customer has paid. Closed_success means that the money has also been paid out to your account.