SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d83b6388a5a06c26203873d203a1c7bdc08061fabe451ea276eea61fc241f57' 
  AND token = 'Oro/zQAyWSrggU3lQkCEg0uZVEkTPaJ8abKLq8w05II=' 
  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"
    }
  }
}