You by mistake used curly brackets instead of parens, so your %testhash does not have 'key1' or 'key2' keys at all. It is ({some hash ref} => undef).

update:

use strict;
use Data::Dumper;
my %testhash = {
  'key1' => 'val1' ,
  'key2' => 'val2'
};
print Dumper(\%testhash);

###

$VAR1 = {
          'HASH(0x2251b0)' => undef
        };
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