SQL, delete only if exactly one row is found - mysql

Question

I have a nested query that deletes a row in table terms only if exactly one row in definitions.term_id is found. It works but it takes like 9 seconds on my system. Im looking to optimize the query.
DELETE FROM terms
WHERE id
IN(
SELECT term_id
FROM definitions
WHERE term_id = 1234
GROUP BY term_id
HAVING COUNT(term_id) = 1
)
The database is only about 4000 rows. If I separate the query into 2 independent queries, it takes about 0.1 each
terms
+-------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+------------------+------+-----+---------+----------------+
| id | int(11) unsigned | NO | PRI | NULL | auto_increment |
| term | varchar(50) | YES | | NULL | |
+-------+------------------+------+-----+---------+----------------+
definitions
+----------------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------------+------------------+------+-----+---------+----------------+
| id | int(11) unsigned | NO | PRI | NULL | auto_increment |
| term_id | int(11) | YES | | NULL | |
| definition | varchar(500) | YES | | NULL | |
| example | varchar(500) | YES | | NULL | |
| submitter_name | varchar(50) | YES | | NULL | |
| approved | int(1) | YES | MUL | 0 | |
| created_at | timestamp | YES | | NULL | |
| updated_at | timestamp | YES | | NULL | |
| votos | int(3) | NO | | NULL | |
+----------------+------------------+------+-----+---------+----------------+

Answer 1

To speed up the process, please consider creating an index on the relevant field:
CREATE INDEX term_id ON terms (term_id)

Answer 2

How about using correlated sub query using exists and try,
DELETE FROM terms t
WHERE id = 1234
AND EXISTS (SELECT 1
FROM definitions d
WHERE d.term_id = t.term_id
GROUP BY term_id
HAVING COUNT(term_id) = 1)

Answer 3

It's often quicker to create a new table retaining only the rows you wish to keep. That said, I'd probably write this as follows, and provide indexes as appropriate.
DELETE
FROM terms t
JOIN
( SELECT term_id
FROM definitions
WHERE term_id = 1234
GROUP
BY term_id
HAVING COUNT(*) = 1
) x
ON x.term_id = t.id

Answer 4

Hehe; this may be a kludgy way to do it:
DELETE ... WHERE id = ( SELECT ... )
but without any LIMIT or other constraints.
I'm depending on getting an error something like "subquery returned more than one row" in order to prevent the DELETE being performed if multiple rows match.