SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfb945df87a65a7b4fe46f6d07510e7f80499c3c5c8302aa06628707c878cf81' 
  AND token = 'PHDRhVNVAjWmlH/0LcaVKe1SvIyxRVY9BOU6gCBkDmE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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