How to identify in DB what files are locked?

In my Nextcloud MySql database I see:

mysql> SELECT count(*) FROM oc_file_locks;
+----------+
| count(*) |
+----------+
|     3145 |
+----------+
1 row in set (0.00 sec)

mysql> select * from oc_file_locks LIMIT 3;
+---------+------+----------------------------------------+------------+
| id      | lock | key                                    | ttl        |
+---------+------+----------------------------------------+------------+
| 1964699 |    0 | files/7aef25a3f658b21883b3e0ca3a140142 | 1726241270 |
| 1964702 |    0 | files/2d4f75e0597d74c589c6f900fd014e3b | 1726241269 |
| 1964784 |    0 | files/a2d7c6240d5bbfb529d1494588e12ec7 | 1726684205 |
+---------+------+----------------------------------------+------------+
3 rows in set (0.00 sec)

mysql> SELECT fileid, storage, path, path_hash, parent, name, size, etag FROM oc_filecache LIMIT 3;
+--------+---------+--------------+----------------------------------+--------+--------+---------+---------------+
| fileid | storage | path         | path_hash                        | parent | name   | size    | etag          |
+--------+---------+--------------+----------------------------------+--------+--------+---------+---------------+
|      1 |       1 |              | d41d8cd98f05b204e9805998ecf8427e |     -1 |        | 5802024 | 66e40d7bd7b0c |
|      2 |       1 | files        | 45b963397aa30d4a006330d85e4fe7a1 |      1 | files  | 5802024 | 66e40d7bd7b0c |
|      3 |       1 | files/Photos | d01bb67e7371dd49fd06bad932f521c9 |      2 | Photos | 3157336 | 5c443f7c90e4e |
+--------+---------+--------------+----------------------------------+--------+--------+---------+---------------+
3 rows in set (0.00 sec)

What should look like the SQL join between these tables? i.e. what is the join clause?

e.g. this doesn’t work:

SELECT c.* FROM oc_filecache c JOIN oc_file_locks l ON l.key = concat('files/', c.path_hash) LIMIT 3;