SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe9f5b30fd4a645815beae616f5e742660569d771223ed66cd1ab49c99b9fd0f' 
  AND token = 'HQ1KfTSfmbh7UtOoLvcg9QFJjcAZnbmy9EmTkjIsKJ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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