SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a91303284e2ee90ded189ea9a1cabf8ea81f48c78e3e569c67184d1fdd267b7d' 
  AND token = 'xYB8xOEkO7tvurmKs6ZmDK1ohEV53ZFbihzC+34CVRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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