What is an example of a plant species that is a halophyte with seeds that germinate quickly?
It turns out that your research question about halophytes has been asked many times before. You should learn from your predecessors... 

Seed germination in halophytes displays a high degree of inter- and intra-specific variability. However, Khan &amp; Gul (2006) report that germination patterns respond to a number of environmental factors (including temperature, NaCl concentration, and presence of different regulating chemicals). 


Their paper has over 100 citations, many of which cite germination studies of numerous halophyte species. I'd recommend you start your search there.  


You'd also probably benefit by perusing the sources in Ungar (1978) and Panuccio et al. (2014).



Citations


Khan, M.A. &amp; B. Gul. 2006. Halophyte Seed Germination. In Halophyte Utilization and Regional Sustainable Development of Agriculture. pp.11-30
Panuccio, M.R., S.E. Jacobsen, S.S. Akhtar and  A. Muscolo. 2014. Effect of saline water on seed germination and early seedling growth of the halophyte quinoa. AoB PLANTS 6: plu047
Ungar, I.A. 1978. Halophyte Seed Germination. Botanical Review 44(2): 233-264