SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47890c7dcf1b41a1de3f6f03127889a8340ed913cdca950b73b5ee921f1925d0' 
  AND token = '/XXfcFCSVT4QFOJ7JGGy3tYy+UxxrcudJxx0t2If+eU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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