SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82d9b9979ca8b1b54f78e888938766af97480a79b41b8794c391e891da99e01a' 
  AND token = 'MCszJqinuJ3HQ17zIcgbQJeqJvAUATOvQIT5Lqh7P08=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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