SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfac58ad05cdd796c0850bcfbae0daf75bfdbc68cf852ae79eaf611ac3df6fbb' 
  AND token = 'O9xyIHy5IU1wFCErDxjKADruhXebcdt50JZQoO/csho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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