MySQL: Where there is no corresponding value

Using MySQL., how can I select `contacts`.`contact_id`where there is not at least one `contactsinterests`.`contact_id`?

This produces the correct results however it is slow, taking more than five minutes to run this single query:
SELECT `contacts`.`contact_id`, `contactsinterests`.`contact_id` FROM `contacts` LEFT JOIN `contactsinterests` on `contacts`.`contact_id` = `contactsinterests`.`contact_id`
WHERE `contactsinterests`.`contact_id` IS NULL

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ste5anSenior DeveloperCommented:
Then you should take a look at the table DDL. Seems that contactsinterests has  no index (foreign key?) on contact_id. btw, does contacts has an index on it (primary key?)?
zephyr_hex (Megan)DeveloperCommented:
Your query is correct, so as @ste5an suggests, you should look at your indexes.

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MySQL Server

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