SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d83b1f163104b7774f3d125c3460d043570d027549c8421cb80bd323eb3a283' 
  AND token = 'wB/juNZZvKKMMul+7hWH+a9FNOkwVqSWZNiUHRXSVQU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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