module ActiveRecord::Integration

Product.find(5).cache_key # => "products/5-20071224150000" (updated_at available)
Product.cache_versioning = false

the cache key will also include a version.
If ActiveRecord::Base.cache_versioning is turned off, as it was in \Rails 5.1 and earlier,

Product.find(5).cache_key # => "products/5"
Product.new.cache_key # => "products/new"

Returns a stable cache key that can be used to identify this record.

def cache_key
  if new_record?
    "#{model_name.cache_key}/new"
  else
    if cache_version
      "#{model_name.cache_key}/#{id}"
    else
      timestamp = max_updated_column_timestamp
      if timestamp
        timestamp = timestamp.utc.to_fs(cache_timestamp_format)
        "#{model_name.cache_key}/#{id}-#{timestamp}"
      else
        "#{model_name.cache_key}/#{id}"
      end
    end
  end
end