The 19-year-old appeared in the League Cup against Newcastle United earlier in the season and is expected to play against Chelsea on Wednesday.
"I've been training every day. Working hard and getting fitter every day so it's going well. When you go on tour and play a few games, it gives you a good taste of first-team football and it just makes you want to play more when you get back," Keane told MUTV.
"I know there's probably only going to be one or two opportunities because of the players involved but I can't think like that. I've just got to work hard every day in training and prove I'm good enough to play and, hopefully, get picked.
"A lot has happened in the last year but it's been good experience for me. I keep stepping up a level and, hopefully, that will keep happening and I can progress with England and keep getting my chances here in the first team."
Keane's twin brother William, also at United, is currently out with a long-term injury.