SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3fce36d1a4f9e94bc19a694d0b4672fa8db4ce4b633e69b8a541f12da74435f1' 
  AND token = 'PKjV8XqpBwraVzr9tdcuC8KZd0nAV8z20x55KSvt9SA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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