This looks like a miner payout address for MegaBigPower (see the configurations: config #1, config #2)
{
"isvalid": true,
"address": "1K7znxRfkS8R1hcmyMvHDum1hAQreS4VQ4",
"scriptPubKey": "76a914c6c500a363006915700742e34ab21921a2923ecf88ac",
"ismine": false,
"iswatchonly": false,
"isscript": false
}
{
"result": {
"confirmed": 0,
"unconfirmed": 0
},
"server": "localhost"
}
{
"result": [],
"server": "localhost"
}