Not sure why the URL is not quoted, but have you ever tried something like this?

echo '{\"id\":01,\"start_time\":\"1477954800000\",\"stop_time\":\"1485
+817200000\",\"url\":\"http:://www.example.com\"}' | perl -nle's/\\//g
+;s/:(?!:)/=>/g;$s=eval$_;print $s->{start_time}'
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