I use Gore softshell overshoes and toewarmers with your regular ventilated road shoes and I like this combo down to low 30s for a couple hours.
For longer ride times or lower temps I'd go for a pair of winter commute boots (Northwave, Diadora, Specialized, etc.)
Northwave Celsius, for example: http://www.amazon.com/Northwave-Celsius-Arctic-2-GTX/dp/B00WWSIGK4/ref=sr_1_3?ie=UTF8&qid=1447783083&sr=8-3&keywords=arctic+gtx+2