SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83cab0ab9674f262acd09a6339ef8da38373c32ff416836dbdf37caa0379d759' 
  AND token = 'mVzUxGlohiKDLvx/IyiojY+tMDBPLGX/2KE7kHatpWQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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