1. A system, comprising: at least one processor; one or more memories having stored thereon computer-readable instructions that, upon execution by the at least one processor, cause the system at least to: store a data item in a database, the data item indexed in the database by a first token; validate a request to modify the data item, the validating based at least in part on the first token and a stored association between the first token and information indicative of ownership of the data item; remove the stored association and generate a second token in response to the request to modify the data item; store the modified data in the database, the data item indexed by the second token; and store data indicating that the first token is invalid for accessing the data item.