SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '687b6270482e506c498c94c79b061a7513a15168a9f0d6edf8db845771be78a9' 
  AND token = 'wYWZLAvKAlJzBaUaPZdjqEqFv4N+OBAid85hbAIxHmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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