SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '576bc3afc952fda91e5834dbc39ca641fc6a194988fe74e080fe1b309ea2e911' 
  AND token = 'NwRvQZxaTnGsaa3NsEWfDhK3BByuyEi7V8EeLCyvuoo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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