Mysql huge table vs small ram allocation

We have a percona mysql database where one of the table which is touching almost 26.8Gb in size. The server is just 4Gb but its specifically only hosting mysql. Now when I am trying to run a simple query on this specific table is takes almost 5 minutes. Before increasing the ram is there anything else I could optimise. The current settings > innodb_buffer_pool_size=3072M . This table is actually partition too. Here the required information as suggested in the different paste bin 1. SHOW GLOBAL STATUS; - https://pastebin.com/5ijQ01Aj 2. SHOW GLOBAL VARIABLES; - https://pastebin.com/tWt7UjdV 3. SHOW FULL PROCESSLIST; - https://pastebin.com/xPEwVAHs 4. SHOW ENGINE INNODB STATUS; - https://pastebin.com/yj03VWMc But the weird part after I restart the mysql this particular table now is accesible. So what could be wrong here.