During the restore, the process seemed to hang (the size of the database in /var/lib/mysql wasn't increasing), and I ran SHOW PROCESSLIST in mysql to see what was going on. It showed a query in the state of "Repair with keycache", with the Info field of:
/*!40000 ALTER TABLE `xf_search_index` ENABLE KEYS */
What should I do next? I'm using ElasticSearch with XenForo, so perhaps there is some way I can avoid this? I found this old post from Kier which seems relevant, but I'm not sure.