I live about 20 min from STL. For those early am flights, arriving 45 min. ahead of time should be fine, esp. if you've pre-printed your BP and are carry-on-only.

IF the security lines look foreboding, as you're standing at the entrance to them ("them" meaning either the elite- or non-elite lines), ask the TSA person at the entrance to the line if the "B" concourse entrance is open (read: currently staffed by TSA at the time). If so, bolt over there, since few know or remember it, there's hardly EVER a line, and it's a short hallway over to the C gates. It's this one- or two- lane purple-carpeted (floor/walls/ceiling) tunnel thing (sort of like the "fake" plane tunnel into the C concourse, without the plane windows & smaller).

Plenty of STL airport area hotels have park & fly rates if you want to just get here the night before, maybe snagging a stay credit at your hotel program of choice in the process.