Hi, try this! ;)
I think it is more flexible that your code because it needs not your file lines' to have exactly one specific format.

use warnings;
use strict;
use Cwd;

my $path=cwd();
my %Hash;
my $line;
my $seconds=0;

my $pathC = $path . '/data.txt';
open INFILE, "$pathC" or die "Cant open file $pathC\n";
while ($line = <INFILE>) {
    if($line =~ m/.*(\d{2}):(\d{2}):(\d{2}).*/){
        $seconds = 3600*$1+60*$2+$3;
        $Hash{$seconds}=$line;
    }
}
close INFILE;

for my $key (sort { $a <=> $b } (keys %Hash)){
    print "$Hash{$key}";
}
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