SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1adf2548841f255a5a67e836125c3bc46754455d99b84a9a99f287f16d152274' 
  AND token = '4r6rZ11T0sTAn7mT/f1WYoRgHa13yObY247N6Lp/eFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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