SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '992b3e89e2eab1092a141b338f68ee6ed555293d9aced8ecfd3af2139a9fd774' 
  AND token = 'z6MblsqqjACwgEYCxaJMw4cdvZ2mEist3KoNGuDpRlY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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