SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7a9428505e49c42b0c236ebf27f067aad1078f5e708a7d9e0cda492b21d33646' 
  AND token = 'MD48VWq+k2ia3XpqFnFKJnyIMiY9bwQpp0IWqF1LK0c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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