SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '099f9f9a5471596869587e889248672a0b3d4d88d81407e75e81a453af862af9' 
  AND token = 'ADx2jdOI0LK1nJYdVQ1bTgA+yvQhOthneLBNqulVJho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}