This is where you would use table.find which is a function that accepts two arguments: the table to look through and the value to look for in the table. The function returns the index of the value in the table if it is found, otherwise it will return nil:
local tbl = {"a", "b", "c"}
if table.find(tbl, "c") then
print("c was found in the table") -- this will print
end
if table.find(tbl, "r") then
print("r was found in the table") -- this will not print
end