SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '17338c33b34f48ecc674706f9d179f762d049b4cbccab705dee3962b50838217' 
  AND token = 'UxisuQGJIQx0LRcCZc+mqw4VVh88iJ8CvWu7eZaBGvw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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