SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '568711dabd86d7f76bbae206b515dc80eb76321eccb481d34cca29a95aadfdee' 
  AND token = '4Rymbl1WVADhYCokdfG02WnuZg1ZiYK66xI42BJNG6U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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