SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ce19a1648914f1e964bdd717d58f110006f1b11ed06bc4b43138325a7dab292' 
  AND token = 'oN+aOGRHVezrGmw0FL3oLrTwemu24ezXpjmkh1baIY4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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