SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd638294e090e2ee31d4501a3b63f681976174af7d1959804336064b22ea46e18' 
  AND token = 'HuA5cexRY3SmVQggMpLYh+wA5xyW7UfmuEAVsH+tUrk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

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