It depends on what you mean when you say you want it to "support queries", but then also ask for a "nosqldb". It really depends on whether you want a full query grammar (in that case, why not SQL?), or if a key/value store is enough.

I use lmdb pretty extensively. It is single-file (well, it has a lock file) key/value store, can be read-from/written-to by multiple processes, and embeds nicely. It has Python bindings, but I've only used it from C.

https://symas.com/lmdb/