Yes you can eat year old candy canes.
I always have leftover candy canes that are a year old and sometimes older and I eat them without any health issues.
The candy canes are still good for a few years past their use by date.
Candy canes actually have a pretty long shelf life but they just recommend selling them or eating them by a certain date for the freshness of the candy canes.
The candy canes have nothing in them that would actually spoil and make you sick when you eat them past the expiration date.
But they may lose some of the flavor past their expiration date but the candy canes are still okay and safe to eat.