SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '991e50b5bc184486ffa2c92506bf61d7805f8cb0b28ee764468f59c63506d92e' 
  AND token = 'q3elt7jXnARZ441jECWYRh+0lOrLFpM5W5hsKFmhBzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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