SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae7b57250be5dbbd35d9ce3920209d38e69bb46227372122910f88a6f71cf67f' 
  AND token = 'qANJ/v558ekjf2kOIxgzHeIrZp50Grv3z4GB8jMpkf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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