I wouldn't rely solely on color to indicate state. There are various reasons why this is not best practice, such as color blindness.
I would recommend adding more visual cues to indicate the state of the link.
If the item when in a selected state is not clickable, then remove the underline. Underlines have traditionally meant that the text can clicked. Removing that would would correctly show that the text can't be clicked on, while also creating a clear visual distinction with the other link.
Other visual cues you could consider:
- Increase the thickness of the underline so that the selected item stands out
- Increase the font weight of the selected item
- Invert the colors of the selected item so that the background and foreground stand out