SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e506b97675012978bfa3cad6bc3e07e7795d479f1ef357e978260ae0d8feae50' 
  AND token = 'jI9r5VnIz38nc1y63nDGvHUZWHnqoMrvBz9sT1FBJJE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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