SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23c8b59303e0df10f8103566ddd7fb26f4f534337ccdab1d572b8f48f845a04e' 
  AND token = 'vP4S5b3BLYa3ulRSSPgsI/vQJ+9hfiYtMVz5ej2xQoI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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