SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5e349a470ba48dcef807c9401adbaf96574593d48cc95df5ad2ffe8592338b5' 
  AND token = 'MDIq/myTnpM1+YvkRH1HlfphRFpzhJhVm6T1OvHWyKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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