SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a797d9cd1d35b43cf2b6b5416d567c2f775c63f42a4f1db05db6ae6902876f29' 
  AND token = 'xwl8wjG/ZOjLDrPtnd5Lt9uvVdPmEUtBiYJrT+2hvlo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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