Eels are very tough!
As long as your eel is breathing, it should recover on it's own in time. If you want to add some Prime or other additive that aids in the slime coat for the fish, you could do that but I would just let it recover without too much intervention.
I had a similar experience happen with a Jewel Moray and it made a full recovery.
I moved home from Chicago to west-central WI in December of 1992; about a good six hour drive. I moved both of my tanks with me so I had fish in multiple 5gal buckets on the floor of my car with battery-powered air pumps. I left Chicago just before a snowstorm hit and by the time I made it home, I just dumped the fish into a couple of tanks I had set up when home during Thanksgiving break.
When I woke up the next morning, I found the eel stuck to the cold concrete basement slab; the glass cover didn't completely cover the tank. The eel was cold and unresponsive, so I placed it into an old bread bag. Before I pout the eel into the freezer, I decided to measure the fish to see how big it had grown; it was my first saltwater fish purchase. As I laid the eel on the counter, I felt a muscle twitch so I immediately ran back to the tank. I threw the fish into the tank. I was using a Piccolo protein skimmer (who remembers those; small wooden airstone tube with a collection cup) on the tank so I removed the collection cup and placed the eel's head into the tube to receive a full blast of water and air; yeah, I was panicking! After what felt like forever (likely a handful of minutes), the eel was breathing on its own and spent the next couple of days just laying behind the rocks.
The eel made a complete recovery. The only evidence of the ordeal was a small scar from one of the places the skin had stuck to the concrete.
So give the eel some time to recover. They're tough!!!