SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c4023d0bbaede001741d0401609c7f359a7850ce6f07e0e440ccf89bd910dd1' 
  AND token = 'JDoHe9eAprrGURzXjXTCii7rF+T0QTtC+uj9Vf38nAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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