SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '768356a04c6fcd875eca85fa1face9df42238520b3dd9ce47dc6850e8bd216fb' 
  AND token = 'kG92lugkyPKaXQUISNAvwWyNL6Hq5ar6iTO8VlDEen0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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