SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3db675cbf82d26a1d942cb8e3fba440c1e7bd8c4d993cde7bae0f88370f6ba6' 
  AND token = 'rwSChPlBw7K1vJq67raj3nlLMbi0WrBTmi5nSwQKVXY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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