Высокий лимит записей

$sql = "(SELECT (UNIX_TIMESTAMP(timestamp)*1000) AS time ,IFNULL(hodnota,'null')AS temperature
FROM arduino_data ORDER BY timestamp DESC LIMIT 60) ORDER BY time ASC";
$result = $conn->query($sql);

if ($result->num_rows>0){
$count =0;
echo '[';
while($row=$result->fetch_assoc()){
echo '['.$row["time"].',' .$row["temperature"].']';
$count++;
if ($count<"60"){
echo ',';
}
}
echo ']';
}else{
echo "[[],[]]";
}
$conn->close();