SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2596bbbb3d8fc22560b633fb8e72b62b708bccc3668e7ca376d1b81012baff3f' 
  AND token = '9Ke5U4aYaeW4CYyjeYBd9ZvDVIRxhOI77Egnmk/BqTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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