use strict;
use warnings;

my %row;
$row{test_name} = '{CHK.test: 1 2 3}';
if( $row{test_name} =~ "CHK" )
{ print "CHK-------"; }
[download]

Prints:

CHK-------
[download]

for me. How is your code different from the code that I copied from your post and added a couple of lines to for the sake of tidyness?