This is where i like to use Time::Piece (Time::Seconds contains useful constants)

use strict;
use warnings;
use Time::Piece;
use Time::Seconds;

my $date_from_db = some_magic_function();

my $one_hour_ago = localtime( shift( @_ ) || time ) - ONE_HOUR;
my $db_date = Time::Piece->strptime( $date_from_db, '%Y-%m-%d %H:%M:%S
+' );

if ($db_date >= $one_hour_ago) {
    # process
}
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L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)