At the moment, I do not have access to the current database of registered brands in Russia, such as the register of Rospatent. To determine whether the Nexus Market brand is registered as a trademark in Russia, it is recommended to perform the following actions:

1. Visit the official website of Rospatent nexus market and use their search engine to search for registered or declared trademarks with the name "Nexus Market" or similar options. In the database, you can search by name, applications, classes of goods and services.

2. Check the availability of registered brands in specific commodity classes related to retail trade, marketing services or other areas, where the name "Nexus Market" is used.

3. Contact specialists in the field of intellectual property in order to conduct a professional search and, if necessary, register your own brand.

If the Nexus Market brand is not registered, then its use for commercial purposes does not violate the rights of other owners of registered brands, but it is recommended to make sure this to avoid potential claims.

Please note that the information is constantly updated, so it is better for the final answer to contact official sources or lawyers in the field of trademarks.