In my perception and fields, quotation marks are reserved for lack-of-a-better-word descriptions and the rare verbatim quotation. Newly defined terms are italicised instead, e.g.:
We convert these subsets into tokens, which capture only high-level features. Tokens can have a variety of properties...
Before blindly applying this, you should check other publications to see what is common and the guidelines of your publication venue as to whether they address this.
Even when italicising it is important to phrase defining sentences in such a way that facilitate recognising them as such, which does not necessarily require an explicit definition. To decide whether your example sentence meets this requirement, I would have to know more about the context (and probably your field).
That being said, there is nothing wrong with explicit definitions and there exist dozens of short phrases and similar that can be used for this, for example:
We convert these subsets into entities called tokens that capture only high-level features.
We convert these subsets into entities that capture only high-level features, which we denote as tokens in the following.
We convert these subsets into entities that capture only high-level features. These tokens can have a variety of properties … [not really explicit]
(Replace entities with whatever is appropriate from the context.)