SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6be43072837a137075f6b5ef90fb793a4724e54cb3634f8ab2248292dc451e1f' 
  AND token = 'MwsjRu7rJMTvgIukSuLgJiKDMwSPj7Y521UA4jBQrb0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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