My first suggestion is that you do not start an application by creating the GUI. Start with a simple command-line script which will solve your problem, and make sure it works; they you can play with UI.

Now, the fastest solution is, IMO, the use of CDB_File. It will return data in a fraction of millisecond.

It usually takes two scripts: the first one is used to create a CDB file from your data:

    use CDB_File;

    $t = new CDB_File ('t.cdb', "t.$$") or die ...;
    $t->insert('key', 'value');
    $t->finish;
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The second script simply ties the CDB to a hash and look for a key:

    use CDB_File;

    tie %data, 'CDB_File', $filename or
            die "$0: can't tie to $filename: $!\n";

    if (defined $data{}) {
      # ...
    }
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That's it! The fact that it doesn't require a relational database will make it easier to set up your application. Think about that!

Finally, take a look at Tie::File::AsHash -- it can be usefull.