How do you deal with coding interviews in which companies ask the question which generally take 3-4 hours if you haven't practiced/memorised the same problem in recent 1 months? (You know, you can solve it but you need more than 1 hour). For example, I was asked to develop https://todomvc.com/examples/react/#/ (To Do App) in 45 mins (15 mins gone in intro + closing questions) and I was left with css and one advanced functionality, and I got rejected.

Asking to develop a full-fledged Todo app in 45 minutes isn't something any good company would tell you to do in the interview. It is a flawed evaluation method IMO. Even if one manages to do it in said time, the implementation would be crappy at best and interviewer would never know if the candidate can ever write a cleaner solution. Typically, companies ask standard DS problems in these interviews (AKA Whiteboard interview) where you're not expected to write a running code but should have a functional pseudo-code which solves the problem.