First, I store the lengths of columns to the @lengths array. I then create a template for unpack to process the table.

#!/usr/bin/perl
use warnings;
use strict;

use Data::Dumper;

my $header  = <DATA>;
my $pattern = <DATA>;

my @lengths;
push @lengths, length $1 while $pattern =~ /(\+-*)/g;

my $template = join '', map "A$_", @lengths;

my @names = unpack $template, $header;

my @table;
while (my $line = <DATA>) {
    substr $line, 0, 1, q(); # Remove the leading space.
    my %row;
    @row{@names} = unpack $template, $line;
    push @table, \%row;
}


print Dumper \@table;

__DATA__
app      db    comment    time      blabla
+--------+-----+----------+---------+------
 one      a     rge        00:00:00  DFDF  
 two      b     fghfjjf    00:00:00  fgfg  
 three    cc    fjfjfj     00:00:00  fh    
 four     ddd   fjgkk      00:00:00  tjku
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