SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8fc729713d62a81e3b7db3593703f08bfa3348150683504ceab7fff63dfc777' 
  AND token = 'fAQUuTmA0WBVI1alEQjtXBvc9dg5wayzJKx7671QFjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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