Indexing queries with bit masks

I want a column in my Users table that will keep track of which types of
notifications the user wants to subscribe to. There's probably about 10
different types, so I don't want to have 10 boolean columns because this
seems kinda hacky and makes adding new types more work. So I'm thinking
about using a 32bit integer type and storing the data as a bitmask.

When a certain event happens, let's say event 4, I need to query for which
users to notify. So I'll be doing something like:

SELECT UserId FROM Users WHERE Subscriptions & 8;

(I haven't checked this syntax but I'm assuming that's how you do it)..

My question is say there's a million rows in the Users table. If I have an
index on Subscriptions, will this index be used in the above query? Is
there another good way to make this query super fast, or is my approach
totally dumb? I haven't implemented this yet so I'm open to new clever
ideas. Thanks!!

Mike