SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c6d2a51e361e9fc91168311a93a20f00e3873fbeb2e4f72d5aaa382db1266b6' 
  AND token = 'koojYLC05aSzO1Kxhk+jlDmwaU/VzF0VXugDmtwbOLU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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