SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '550bfb118ca683daf99f2f7581eb74239e80ceba62798dbd02d03a70cb4c39c7' 
  AND token = 'wLXciwiUl0E/GxfBIKVyAeEZhJb5xjwUOVAO/hz48QA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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