SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'acd7136d5c593ea4f3713c352897d1e8c5e9756918935121357cb07c414c3ff2' 
  AND token = 'bkTHp4QmKqoGzIMgB0X6lqfgrpcfN0T1kuj1xpyeNEk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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