complexity of CSPs with 2-variable constraints and multi-valued variables
With 3 values and binary relations, the CSP is still NP-complete (it is denoted with (3,2)-CSP). A quick reduction is from graph coloring:

add a variable $x_i \in \{1,2,3\}$ for each node; then for each edge $(x_i,x_j)$ add the constraint $x_i \neq x_j$