SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75dfa9489d9a02d1f4f9f6f014fba3201970e7dd5748166289d07bf3a8adad68' 
  AND token = '7k1dFu3Kimh3RV8mF6UqMj1+tJ65KOIr+KG5IMHp+uA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

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