SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f6c190531543e7b214b41c797aa0fff9e57957aa318054c0dd7124259942a29' 
  AND token = 'kk7gfWd+W08NwuY3Mw/3uMARZ9PvDo1lGblufW23Wuc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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