SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f12dbe4fb59ea36c2e8f217c14924dd2a36626152d6f9f5ff8f8f1742bf570f2' 
  AND token = 'Kp5HGURm+7sYl2PWjiCyrh6ClcWtxx4/IAHgqz2RlpA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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