SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f954ee18665a0b36a9286dee37f415ff70ace9d665eab4f133b7030f7c8c27d' 
  AND token = 'qPaZKoenzzMDhzCquqFBGPVnHxTZW6OTYpGNmZ60+5k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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