SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c683adeeaa01674dd1e1809349e1c74c7ee075fa83777d6a0db18e52a4ccaa3a' 
  AND token = 'lePoDqm1RR39S432IYPhakpDlAza3Q33oiKW5BWQHHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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