The type of database that uses a structure allowing for efficient data retrieval using keys is known as a key-value database or hash table. These databases store data in a format where each key corresponds to a specific value, enabling rapid access and retrieval. This design improves performance for applications that require quick lookups, such as caching data or managing user sessions. Examples of key-value stores include Redis and Amazon DynamoDB, known for their scalability and efficiency in handling large volumes of data.