Select latest 2 articles, but only from given category

Try the below code-

SELECT p.*, t.term_id
FROM wp_posts p
LEFT JOIN wp_term_relationships rel ON rel.object_id = p.ID
LEFT JOIN wp_term_taxonomy tax ON tax.term_taxonomy_id = rel.term_taxonomy_id
LEFT JOIN wp_terms t ON t.term_id = tax.term_id
WHERE tax.taxonomy = 'category' AND post_type = "post" AND post_status = "publish" AND t.term_id != 56
ORDER BY ID DESC LIMIT 2

Hope that solves your problem.