After looking up the ingredients in a no bake cheesecake box mix, you should be able to tell by smelling the mix. If it smells acrid like rancid oil or butter, throw it out.
I often find that there is a build up of dried milk around the container opening that smells sour. When I'm in doubt about the milk in the container, I pour some into a glass and then smell to see if it is still fresh. More often than not it's still ok but keep in mind that it would be a good idea to drink soon or keep it for baking.
I always smell and do a visual inspection of expired items before cooking or consuming. When in doubt, it gets tossed out. So far I've suffered no harm.