Many years ago, I adopted a cat that was removed from a similar situation. The cat's name was actually "Hyper" and her owner used to put her in a carrier, cover it with a towel and blow pot smoke inside. This was done to her repeatedly (like nightly) for a few years. She was about 5 years old when I adopted her.
I researched the situation when I adopted her and found out that pot doesn't have the same affects on cats as it has on humans. In fact, catnip affects the part of a cat's brain that pot affects in humans. So when you give you cat the nip, you are actually giving them the equivalent of a pot high.
So unless there was other trauma to the cat by putting it into a small box, then the cat should be OK. Doesn't take away from the fact that the owners were abusing the cat and should be punished accordingly.