Use a tag search, something like this:
danbooru.donmai.us/post/index.xml?tags=status:any+md5:e455d2ac83382b4e2e5b1c01f5e20ac9
Doesn't include the notes/comments/pools.
You can search for several md5s at once, just separate them with commas.
Read the cheat sheet for some other ideas.