SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '620324a22cbfde49cbfa5b9b25ee827bfa0ebc3232f46286540328f832455797' 
  AND token = 'byk04dQT2Jx8HnPQFCCOt2DgY2kCtofVDqugIvOIOiY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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