SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81fc4cb9790f891ca9686d53e8eae60625179ed9c421ccae21fab9dd9732dafe' 
  AND token = 'qT489rs27MLxMvAgtaDSy15H1oCTC7MLFew41JTHeeo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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