SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15b6425f62caac8e7eaf2651fa8aa399183d7a18eaafde459ee80203989fb678' 
  AND token = 'YYtXreziqfjXFWgrLEmja2wFs+jIa/Xh9NCS3uT8C2E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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