i would like to thank Goku for helping me get the coffer key from Ifrit's Cualdron.
The key dropped on the first monster we killed, a volcanic wasp. Then as i was about to start hunting for the chest i thought it would be funny if the coffer chest was at the first spot. Well, lol, it was, and it was only guarded by a Volcanic gas (bomb) so it was real easy to open.
so thats key on first kill, and chest in first spot..... hope i get this lucky on my level 60 AF mobs