SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '999e6b8a7101bbf7164484a4d4306a7947294ec62d321bbfb5b9f63d826c8a9a' 
  AND token = 'Ybb2p4+LJu7cjkKE6SCINkA30pRhCH1PhEjYk0aoAbk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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