SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd02adf2acc21cd14d5107a6469b7ce1a4fc88fed594c388aaa20903ea3ab81ca' 
  AND token = 'CDflsDGGtiBGheXi0fWsqrOhUy6FakgLApWXB8PvJac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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