cache set in custom table not working?
If you are using redis, wouldn't your cache bins not be controlled in the Drupal database anymore? You would therefore need to explicitly set the cache bin to use DrupalDatabaseCache so that it uses the Drupal database in settings.php. 

Example: 

$conf['cache_class_activity_dashboard_cache'] = 'DrupalDatabaseCache';


This is how it used to be done with Memcache... Redis should be the same, but check the README:

http://cgit.drupalcode.org/redis/tree/README.txt?h=7.x-3.x

It would explain why you can query this on your local machine, if you only have Redis configuration set for the remote environments running it. You are querying the database, but the cache is pulling from Redis.

This is for Memcache, but sheds more light on excluding certain cache, like cache_form - which remains in the database. https://www.drupal.org/node/1131468