SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3983601a8c00ab531326c9b38045753539f86e94ac818aa1913e539d2ed6bebb' 
  AND token = 'lPWNF4Gq06G8wXVaXqIse6aVGPgyOn08LUIxMMVJUe0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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