SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9fdf829984c759c37fa47dc5f22eac5f5b6287a6b845215d5eb10996fee56f99' 
  AND token = 'nV3IWug+bfbswZ5V4mHuZLDlFrJupR8mBJndxOdKTIE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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