SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2804000af0f451161970f6f81b7dd547f46a2dc70948b0b7aa9f269c32ab6839' 
  AND token = 'yctn1zBF6ky+yEqRP3djPlrwqrSmVh+gOBRhhRMKl8I=' 
  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