Fix the type of some values passed to MySQL

Summary: Ref T3377. MySQL ignores indexes if we hand it mismatched datatypes. This seems colossally dumb, but give it what it expects.

Test Plan: wat

Reviewers: wez, btrahan

Reviewed By: wez

CC: aran

Maniphest Tasks: T3377

Differential Revision: https://secure.phabricator.com/D6201