SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8372c29c359cfa36d48d8720f320c22edfa909471f4768386cb1f1ffca9f72c3' 
  AND token = 'uX5+ExRoXvwCgl8SxfZNq8UKmVK//RDRzZcMRPQsWfw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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