SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '339146325e627c73308899137db8a22297175b73e0ac17844fbcbe7cb90bf779' 
  AND token = 'WSBUgT/bvTXudeSJ84Vq+a1xP2v/ZBBhXAhzqkvvE5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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