Making use of SQL UNIQUE KEY to prevent duplicates in Wordpress and $wpdb

Question

I'm fairly new to DB architecture, and am creating a basic lookup table with the following structure for a Wordpress application. It simply stores two post ids to associate an "entity" post with a "news" post:

(
   id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
   news_id int (20) unsigned NOT NULL,
   entity_id int (20) unsigned NOT NULL,
   PRIMARY KEY (id),
   KEY (news_id),
   KEY (entity_id),
   UNIQUE KEY entity_news (news_id, entity_id)
)

My application will regularly attempt to store an association that already exists in the database, as there is a background process that regularly checks for new data.

It is my understanding that I can elegantly prevent duplicates by the use of a UNIQUE KEY constraint, rather than manually searching the database for an existing entry and doubling the number of queries. However, Wordpress outputs a a Database error everytime there is a duplicate entry. I know I can disable errors using $wpdb->hide_errors() but that feels hacky and before doing so, I want to check I'm doing the right thing here?

tl;dr

Is it good practice to rely solely on MySQL to detect duplicates using a UNIQUE key or should I also be doing a manual query beforehand to check?