SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '494c71f35586e431ac10eda1982858fd9010074de49e99b5ae657b9ce073a539' 
  AND token = 'jVggLutw1jbw6KKbYiZuUZCAAEn5GchjCJoNS+xVvyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}