SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3808688c8673325281d623703f54f129151bf807168cf30933bc170a30c45f4a' 
  AND token = 'Dx8ZnipjuGcvunvhVq+alW1UKC2DFbaldA6Uf5BRmkA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

Explain
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE Impossible WHERE noticed after reading const tables