SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2e691e2807390e5d490ff47701f126fcca7b231933d55f5369ef4947868b874' 
  AND token = 'jMh8eWZh8tWHm+0vHgAzs/wGZg62Yg/9fFhhA/sMG7M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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