SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38d280f70faf28d51956b5d81732ec99abda4329ef92825ccbd26be25b37139f' 
  AND token = 'tluj+8FKExuXVZCZ9IDgTzsge1D02agfzrJ3PcDxX1Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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