extract some column/value pairs via hstore

In a PL/pgSQL function, I need to extract column/value pairs from a
table ignoring some of the columns.
The excluded column names have previously been stored in an array
"ak", which contains

array['country_fk', 'region_fk', 'id']

SELECT key, value FROM
(
SELECT (each(hstore(town))).* FROM town
) AS nk
WHERE key NOT IN (SELECT unnest(ak));

=====

The above statement produces the desired result but it seems a bit
convoluted. Can this be done in a more elegant way?

=====
PostgreSQL 8.4

example:
CREATE TABLE town
(
country_fk character varying(3) NOT NULL,
region_fk character varying(3) NOT NULL,
id serial NOT NULL,
"name" character varying(50) NOT NULL,
source character varying(2) NOT NULL
)

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Best Regards,
Tarlika Elisabeth Schmitz