I also have a 457 plan with Voya (formerly ING) through the state of Michigan because I'm a part time government employee.
I'm charged a quarterly fee of $10.25.
The passively managed index funds available are a State Street Global Advisors(SSgA S&P 500 Index - .03%, SSgA S&P MidCap Index and SSgA Russell 2000 Index both at .06% fee. To find out the mutual fund fees was a cumbersome process on the Voya website, which overall is fairly poor and not intuitive.
The other fee charged by my Voya state of michigan 457 plan is when you go to make a withdrawal. If you make a partial withdrawal the fee is $25, and if you completely close out and transfer all your money out of Voya to be rolled over to another IRA it is $75. If you create an Installment plan, whereby you are separated from the employment, and of the correct age, then you can get periodic payments without any fee. Also when you are 70.5 years of age and forced to receive the Required Minimum Distribution payments - there will be no $25 fee.