mysqltuner - Write Key buffer hit rate
OK, the hit rate is low.  But let's put things in perspective...  25K writes in 25 days is so insignificant (&lt; 1/minute) as to be the least of your worries.  5K/minute would be a concern.

If you are having performance problems, locate the slowest query and study it -- its indexes, its formulation, etc.

The "key buffer" applies to MyISAM tables, of which you have only 1.  The InnoDB statistics are not listed.

For further discussion, see http://mysql.rjweb.org/doc.php/mysql_analysis