SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '309f7c65179143130b6f0d3808955714453680b201f999698fa6a87c601e17d3' 
  AND token = 'aVQwKn4dceO4VOgrUnq9HQFxDIcJzTCiBvM+AwNM39M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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