To add the og:image meta data tag for Drupal commerce variation products images, use the following token:
[commerce_product:variations:0:entity:field_image:entity:url]
I tried many variants including [commerce_product_variation:field_image] which can be found at admin/help/token under the product variation section. This you would think would work but it didn't! After a lot of time trying different token variants, the only one that seems to work is:
[commerce_product:variations:0:entity:field_image:entity:url]
*UPDATE
To add to this, you can also add the image's height, width and alt tag meta data by using the following:
Height: [commerce_product:variations:0:entity:field_image:height]
Width: [commerce_product:variations:0:entity:field_image:width]
Alt: [commerce_product:variations:0:entity:field_image:alt]
With all these above, you need to make sure that you change the "field_image" part of the machine name of your image field. This can be found under manage fields in your Drupal Commerce product variation type (/admin/commerce/config/product-variation-types) - In my case I used the drupal default image_field machine name.