use mysql SUM() in a WHERE clause

suppose I have this table

id | cash 
1    200
2    301
3    101
4    700

and I want to return the first row in which the sum of all the previous cash is greater than a certain value:

So for instance, if I want to return the first row in which the sum of all the previous cash is greater than 500, is should return to row 3

How do I do this using mysql statement?

using WHERE SUM(cash) > 500 doesn't work