In the UK, licensing on creative works last 70 years after the author’s death – assuming any future copyright holders don’t renew it. As for the rest of the world, I can’t say, I’m not aware of any other country specific copyright laws.
I suggest you take your research off of Eclipse, though, the large majority of what responses you’ll get are where members can think they can create laws and conventions on the spot.
Carim’s reply was accurate:
In short the answer is no, you cannot use 1950’s copyrighted music in your game legally without the express permission from the author or copyright holder. There are quite a few sites dedicated to public domain music; might want to have a look around.