Do you have a question about this? If you click on the host with the red status you will see a more detailed dashboard for that host, which should give you an indication of why the status is red. It looks like it has triggered an alert for CPU usage.
what Plugin specifically designed to collect metrics on MySQL in InfluxDB.
There is a MySQL Plugin for Telegraf that you can enable which will collect a fairly vast set of metrics about MySQL. For a complete rundown of what it will collect, see here: https://github.com/influxdata/telegraf/tree/release-1.5/plugins/inputs/mysql