CSS selectors How to get the index of a particular element

CSS selectors How to get the index of a particular element

I am trying to use a css selector to select and item but only work for
xpath. What would be the equivalent of this xpath to css.
driver.findElement(By.xpath("(//img[@alt='Authorise this row'])[2].click();
If I use the css
img[alt='Authorise this row']
I get a lot of results through say firefinder.
Is there a way like xpath where you can get a particular index of the result?