SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0c830afe01234c0c31442ba7d093a92a58e755665a2bc9b289f9d6ae78d6bd5' 
  AND token = 'sMqAhfva19JNsQunt6ZQMdExcDX5yEzRwi98SObUQng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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