SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '65ddc4a8433a6746d3d424515014698a53bde32f0ee62113999a418ee0c40495' 
  AND token = 'igfTc8HvjIU84UXLUKzHPabDzxR41sidTg7AFkEKVIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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