I think it´s a Green Baron Racer (Philodryas baroni) on your picture. Both species are held in the terarium room in the elephant house. Rhynchophis lives in one tank on the longer side, and Philodryas in a tank on the short side - without any signage so far. I also thought there are Rhynchophis in both tanks, but they looked a little bit different, and only recently I found it´s identity through the annual inventory list.
Thank you for the information Jana, I didnt know about Green Baron Racer. And this one were, as you said, on the short side, next to Rhamphiophis, so you are right.