SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8a5a928db5174c08f42d9e90608e1ccee4ac9baaec9302b14f8e87781b3b4f3c' 
  AND token = 'GX4laJ/3G5XVzBWkT5ZLcOtl3hiT+Sxoz5b8wn6YuDw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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