SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd71437d646ad2ab25979026c2a0894f9d68c4531c098bff80194c2bdbcd5af93' 
  AND token = 'UJJalRV9srr02GH7HgsKXiDZYKHMrtE9lQDZX2tvZVw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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