Man pages matching name ntp.keys in section 5:

ntp.keys.5.en	debian 10 / ntp
ntp.keys.5.en	debian 10 / ntpsec
ntp.keys.5.en	debian 11 / ntp
ntp.keys.5.en	debian 11 / ntpsec
ntp.keys.5.en	debian 12 / ntpsec