SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03321484801e8b9c9eac7cad6aac3ec5c36f2a3d6640ad3578889fce46d88012' 
  AND token = 'FtwcLMyVsAGByxt5F5PYLzUh+KCBIEI0CtC/NuEFNKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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