If you just want to check if the event was in the last 24 hours without using any module, you could compare

my @yesterday=localtime time-24*60*60;
if( (sprintf"%02d"x6, $yesterday[5]+1900,@yesterday[4,3,2,1,0])
  < (sprintf"%02d"x6, $year,$months{$month},$mday,$hour,$min,$sec)
)
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