SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd68437643c78795c89bfdef51e6551ae286c1628f546c3c835a3da25960309f9' 
  AND token = 's0V0mA+rQJ5IrtxfDMfwbtmLI//C9FbFyYhK9+ZukJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

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