SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35e2d70423602313867c16e00eebd5efc14b80879d4bf43d1b848a9ca1163243' 
  AND token = 'QmhnkeEjBLQU0gZnaI+EaoGN0ieEfO1YVQvqwRPPuaM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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