SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b180397635e1912e2dffb16944a0622a43fdeebc8e99666748a124a43670702' 
  AND token = '9v/hoZIHvhbJpOufhUmUjGVKOzKcPBnDvULM3PH707w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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