Why did I pay a different price than the chart shows?

There's no way that anyone could know the answer. You could have been looking at the wrong chart. You could have misread the price. Perhaps the chart was correct but your virtual trader was providing delayed quotes. It's all a guess.

The only thing that can be verified is if you post a trade execution time, it can be determined what the price of the stock was at the moment in time.

The only determinable fact at this point is that EQ has traded between $3.53 and $6.44 today.

EDIT

From your question as well as additional information offered in your subsequent comments:

The chart showed that the price was $5 and I ended up paying $6.17. Did higher volume cause that?

I bought at 18:50 (Central European Standard Time)

The opening price for that one minute was 6.06 x 6.07

The closing price for that one minute was 6.02 x 6.03

During that one minute interval, EQ traded as high as 6.23 (6.22 x 6.23 at 12:50:17)

Circa 12:50:08, about 3,600 shares were purchased at 6.17 in about a 20 or so transactions.

Note that my time stamps are EST which is 6 hours ahead of your time.

Conclusion?

You paid the correct price.

I used market price and I used Thinkorswim papermoney (20min delayed data)

20 minutes earlier than your purchase, EQ was trading around 5.17

Final Conclusion?

The culprit for the confusion here is 20 minute delayed quotes. At 12:50 EST, you were looking at the price in the vicinity of 5.00 representing the price from 12:30 EST (delayed) and a market order at 12:50 EST purchased shares in real time at $6.17.

You bought it around 12:57 PM? This is why I rarely use a 'market' order.