I really didn't think that's correct--though it's been a few years since I did SQL regularly.
SELECT *
FROM articles
WHERE last_updated >= %s
AND created_at IS NOT NULL
UNION
SELECT *
FROM articles
WHERE id IN (1, 2, 3)
AND created_at IS NOT NULL
That should give a list of all articles updated after whatever date (regardless of ID), appended to a list of all articles where the ID is 1, 2, or 3 (regardless of when they were last updated). I would expect to see extra articles that only fit one criteria or the other, and also duplicate articles.
I included the join quote because an inner join would be the way to do this, rather than a union--though it would likely be less efficient than just filtering on the required parameters.
If I'm wrong here, I'd love an explanation of why.
I've only ever seen Chile as the country.