SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f2404e283f9212eefd9427f8d4b75970dc2b5cd74b9bbb25191336ccc081452' 
  AND token = '6caMKmzyFNJvob2wyEmXJmkvI9dFjLAPs5kKJrFG2QE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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