SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8cf5865b2800a945e073b2671ed465b603f072be7d46a10717bc4342d4280c37' 
  AND token = 'KMwK0skf3ayDbrstLesQ/HVD3UOu9xhIJkeomVAN+5Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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