Standard lay pellets are fine - some people keep them on chick starter or supplement with soy to encourage rapid growth, and that can shorten the lifespan of any bird
;) They're not hybrids, they're crossbreds. And NO chickens are bred for long life expectancy, so it's really a roll of the dice.
If you don't push them - pour high protein feed into them, keep them under lights, force molt them, etc - they'll live as long as any other chicken. Which is to...