For those of you annoyed by all the mimics trying to look for the real chest, here's a tip.
If any of you are familiar with the old targeting arrow trick in the Golden Salvage assault (real chest, arrow disappears; fake chest, arrow remains), it works on these Pso'jxa chests even after they patched the Golden Salvage chests.
Target a chest, keep hitting enter. If you're at the right range, you will get the message "You need a Pso'jxa chest key to open this chest". Once that message appears, observe the targeting arrow. If it disappears when you hit enter, it's the real chest. If it doesn't, it's a mimic. Just be sure to stay a bit far away so as not to aggro it/pop it when you hit enter.