SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '61dd011f53a17945bc5cca2732d571af8439822994ec779efaf53d1540a58177' 
  AND token = 'mXumxpjDwGCRLKi5F/4n4GbrzuTD0GmlZRGDPVekVcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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