SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfe4aba5d555541a55b0da09958ea823d085cb71929a1b19585f249a1651a4a9' 
  AND token = 'VjrSmvj0tLC544TG8LnWNwRzBbMVKBrhp4D5Qi/LlqY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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