You can use the cluster representatives (P45148 in your case) which represent UniProtKB entries.
Upload your list of UniProtKB IDs to the Batch Retrieval / IDmapping at https://www.uniprot.org/id-mapping and map from UniProtKB to UniProtKB. Once you have your results, you can customize the layout of your table by clicking on "Customize colums". Use this interface to add a column for EC numbers (and potentially remove columns you are not interested in). Then you can download your results in tab-separated format (among other formats).
Please provide examples when asking about any identifiers.
I added a placeholder example but I’ll find a better one to update.