SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '20b03994831627c13fa793218799c9d0610bb52916ee4aef47b8988c5b844394' 
  AND token = 'jgRb67YLlomxg09QU/1rnVrwrpfVjC1EQTW/cHznEuM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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