SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df66329869589e440aa03a90be110b29778250f9699b2eeecc23624f46f113e0' 
  AND token = 'pn3GFT3BqndRS8uAEU2uTlwZYW6KvzKIBgICnzVfwYo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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