SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b677a8362defb1376a3ba5422501f414f73868b636180296620cb2cf9253542b' 
  AND token = '5JEcUGxwdCJBrQzFLWzAqwJFigi7i4W1ZN+XH5ZOeH4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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