I have same problem and have no idea. Ive tried to give it to everyone"I THINK"and im starting to believe"maybe"the note is only for us to read and to go where it says.I dont remember it saying temple.I belive it says ruins and prison??? not sure

You might be right. I was going by memory of what it said. I also have a key I found in Netherealm on a dead body I cannot use too. Argh! Too many unknown things. What about the lockpick tool? What do you do with it? It doesn't unlock any doors for me.

I have the lockpick tools also and all the locked doors are still locked.Dosent really make sence at all.

I know!

Actually on Earthrealm some doors that were locked before I had the lockpick tool were suddenly open-able once I got that item. But only a few doors.

yeah the lockpick only works on a few doors in earthrealm, it helps with (SPOILERS)........................
The Shirai-Ryu mission that you do for the Lin Kuei. It opens a few huts, but the one that matters is the end hut near the river, you walk in and see a shirai-Ryu but he dissapears and leaves behind a note about them posing as raiden worshipers. This note is needed to find the shirai-ryu the lin kuei will send you after if you take that mission.

where do you find the lockpick?

I have the same problems as you guys. I've unlocked just about everything else. I still have the dead body key, the note for havik, and the lock pick. Though I remember some door opening after I used the lockpick, i dont know if there are more. BTW, does anyone know where the prison and ruins are located in haviks note.

You find the note in the prisons and the ruins is where u put kabals earthrealm map its right next to the prison take the green portal to go between the ruins and the prison.
Also the lockpick isnt for the Shin ryu mission those doors unlocked later on for me and i never had the lockpick and when i started the game over and got the lockpick from the stealth ninja boy it wasnt for the doors they unlock by themself when that mission starts.
I have three keys a red key which is the red hut key opens a previously locked hut it says.
I have the nethrealm key it is a platinum key and says found on dead body in nethrealm.
I also have the Mysterious key which is ONYX coloed like the KYRPT KEYS that u get to unlock fighters which means it can be used for a hidden KYRPT i am thinking the key says it is unknown what this key will unlock.
thats 3 damn keys that nobody ever used now although the game was hacked and i have Onaga playable on arcade mode and puzzle mode i have shuginko 2nd alternate outfit when he is young plus have him in puzzle and i have monster which is another scorpion outfit and have him in puzzle then i have a 3rd outfit for havik and 3rd outfit for lui kang which is his ghost outfit, that is all I have and no jax is not playable he is a MKDA port that explains why he is fightable but his movelist although he has 2 fighting styles and his tonfas he has no specil moves and his move list he has 5 moves for each fighting style which means his move list is actually incomplete u see the names of his styles but his movelist actually only has like 5 moves each so he is not playable. I found all the secrets thankx to the hackers.
But until i find what those damn keys are for i will still say they are superunlockables, well unless those leys unlock what i already have right now DAMN.
well i also have the note and i think its the treasure chest by the portals but i dont think u give it to anyone, also lui kang doesnt talk to you in outworld meaning u have to trigger a mission for him to talk to u in outworld plus i have raidens staff HOW DO YOU KILL SHAO KHAN WITH THE STAFF thats where u use the staff i know that for sure.

Couple of questions....
I.Where is the lockpick?
II.Where is the red key?
III.Where are Motaro & Shao Kahn?
IV.Where are the keys to open koffins KK & MO?
V.Where is the stealth ninja kid?