You can use the built-in function toArray(Data)
to convert it to an array,
then use first(map( ))
to filter out the array items by the name, and get the key.
For more information about map, see https://www.make.com/en/help/functions/array-functions#map-complex-array--key--key-for-filtering---possible-values-for-filtering-separated-by-a-comma--