Create new discount rule, fill fields in „Discount info“ and save.
Discount type „Assigned to categories“.
In panel „Applied to categories“ select category to which products discount is applied.
In this case: "Laminaatparkett".
Add in „Requirements“ panel new „Include / exclude products by price“ requirement.
Configure requirement settings:
Action Type – „Exclude“
Price Type – „Old price“
Comparison Type – „>“ (you can use also type „!=“)
Price – „0“
Save requirement settings.
Save discount rule.