SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cf3c5f252885a02faf6cc75dcd86a594f671479a5f9fcdbfab18116aa9f7f2f' 
  AND token = 'p22pjf8jXSQZ+oLwxbe5x6BbeAEmUE7u9MQjSdylNfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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