SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8b6683e7af4c5d41ec7522d96142aaf620b4982088c6de6636f14f958174d45' 
  AND token = 'XHUKB44I16YazduGwazGPd9RiySbklYs0DWTHlg4oWU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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