SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c33f1be5c89f9b011ee2018b2d1665a8ba711347b7aee5c278ffb042503c7554' 
  AND token = 'YMkKRrfZXQg7M7cevyYD6zjCpj/Rf+VU/KGWBTTl+Io=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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