SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac6c14b7e1d3e0718357fc96d88398e5a9b90404f0c892fd960c44919e382d71' 
  AND token = 'FU02HsswP8Pe4OUwgHSIQCmm9yIx6QQoETDuo5Zy8bo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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