SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6fefcc00914861d8aac03798b71c9a88fac0e9a8e07f382d2572956fb16db3a8' 
  AND token = 'bmpXhuL7rDjG7ubOLHZnNZZsayYZ7PdNhO60wcUqGYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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