SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b9ef2dacc1b15427811f65a47aac8e462280d11958fa7acc7076e43807cfb78' 
  AND token = '6GCRlc6BczZyGt5DfAzA2KWl60jcUDvezHStSChY7Hg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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