How to make a object what can be picked up and when clicked on another object it ends the game?

I´m currently developing an indie horror game and i have a key object randomly generating itself at random places. I need that player can pick up the key and when player left clicks on a door (after key is picked up) "The End" title will show up and game will end. And if someone is kind enough i could use a script what plays locked door sound when player doesn´t have the key. Could someone help me fast, because I need it tomorrow already. Thanks!