Equal, is equal to, equals, are equal to
Solution 1:
Even though the unit is "kilometers per hour," it's not really a "discrete" entity. You can't separate kilometers per hour from one another, and thus the unit acts as a "corporate" noun, where all the component "parts" belong to a larger unified whole. I would therefore opt for the singular:
240 kilometers per hour is equal to (or equals) 149 miles per hour.