SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c8b47cbab905f9c85f63a6d44920fe41b71205dbf7eb06e1b2f6d7b452904f0' 
  AND token = 'flZO/AUlp4U9DFE7jJw+wUsOHVDDrYCTMvagk/E2nHQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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