Porn is an industry that is often attractive to human traffickers, who see it as an opportunity to make more money off those the traffick. There is so much demand for pornography today, that traffickers can easily make an extra buck by forcing their victims to act in the roles. Victims are threatened to ensure that they look like they are enjoying what is happening. It is their traffickers, not them that get paid for it.
You have no way of knowing if the porn you are looking at is from someone who chose to be there or not.
Human trafficking impacts a massive 40.3 million people in the world today, of which 3.59 million are in Europe.