If you would like to allow a specific IP access to MySQL then you can configure this in the Plesk Firewall.

Please do the following:

1. Log into Plesk, click on "Tools and settings" and then select "Firewall"

2. Click on "Edit firewall configuration"

3. Firstly, to grant access to the Plesk Panel, click on the "Plesk administrative interface" rule.

4. This may be set to "Allow all", change this to "Allow from selected sources, deny from others"

5. Enter the IP address that you would like to grant access to the Plesk Panel in the the "Add IP address or network".

6. Enter the port 3306 (default MySQL port) into the available "Ports" field.

7. Click on OK, then click on "Apply configuration" - If you do not click this then any changes you have made will not be applied.

Once you have done this, MySQL access will be limited to the IPs specified.