my %newhash;

for my $href (@data_list){
   $newhash{ $href->{key} } = $href->{value};
}

## If you want to print the new hash ...
for my $k (sort keys %newhash){
    print "$k  =>  $newhash{$k}\n";
}

##</code><code>##

my %newhash = map {{ $_->{key} } = >$_->{value} } @data_list;