Logic App - Convert "YYYY-MM-DD HH:MM:SS" to Milliseconds since Epoch

I GET below JSON data from source with date in "YYYY-MM-DD HH:MM:SS" format, and I want to convert the it to the Milliseconds to Epoch before sending it to destination, can someone help how to do it in Logic App?

Source data:

{
   "result":[
      {
         "number":"123",
         "name":"ABC",
         "created":"2018-09-19 09:03:03"
      }
   ]
}

Desired data:

{
   "result":[
      {
         "number":"123",
         "name":"ABC",
         "created":"1537304583000"
      }
   ]
}