SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08d9ef01b15edffa62b81516f6ea31a44158082664aaabc9dde41c02f694095b' 
  AND token = '8coaZKwmEh+mCGFKkRNexW8QQnOCZ+4dIviifc5Fo1I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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