Does post_meta data need to be unserialzed?

Ideally, post meta should never be stored in a serialized form to begin with, thus making it easy to query. If the code uses the standard methods for storing meta instead of self-serializing it, then each item would be in its own row and easily queryable.

If the data is stored serialized, then you have very few options. SQL is not capable of unserializing the data by itself. You must process it with PHP code.