Park Tool's Cyclone Chain Scrubber:
It is basically a box that you fill with degreaser, open it up put it over the chain, and there are a few brushes on the inside that clean your chain as it goes through it.
It retails for about 20$ on amazon. When putting it on the bike, attach it over the chain, reseal it, and then pedal backwards. 100 rotations should be more than enough to get the chain clean.
Once you are done. Take it off, dump everything out of it, put water in, and run it back through. Once the chain is clean, make sure to put lube on it.