Postgres find by hstore key / value

I have a table create table device_entity ( id uuid not null primary key, name varchar(255), metadata hstore ); This table has entries with 'country' = 'uk' in the metadata field. This query returns all entries where the key 'country' is present in the metadata field. SELECT * from device_entity where metadata ? 'country' How can I select all entries where the key 'country' = 'uk'?