The USBUART component is implementation of a communications device class (CDC) USB interface. This is a USBFS Component with the descriptors configured to implement a CDC interface.
The CY8BKIT-033A supports Full speed USB. Thus according to the USB specifications the maximum effective data rate is 1.2 MBps.
The USBUART does not have any transfer rate limitation, but theoretically the transfer rate is limited by the USB Full Speed (12 Mbit/s- this is bus rate).
The effective data rate transfer is 1.2 Mbps (The actual data rates are affected by bus loading, transfer type, overhead, OS, and so forth).
For more details on this please refer to the page 11 of the USB 101 Appnote : https://www.cypress.com/file/134171/download
You can also refer to the USBUART section of the USBFS datasheet: https://www.cypress.com/file/376416/download
The above appnote also mentions the following: