SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39aa134420885a168f346aa62fb76eb0324d257e9d84be2c6cef4f272868d1b3' 
  AND token = 'nyNJ+wZY0CzPNI2M6KJ9tCKEWNR6Wdzw6R8wM5Fr4I0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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