SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ab9612230262f864b7ee4dcee94aa1bed27c96d9ce9dd6e87c5bd7d9fc1033c' 
  AND token = 'WkSu4g8GF1W+zqWMZo9fsiYHMGQgtXPQRtd5+Iv5Vuw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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