SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfa5e29285c5931b9a087296591004b822f3c6ae23875807063f4976ea216727' 
  AND token = '4JH30d+7AYzcstEUPcAVUpSEUi4O8RfguMrS/rFxjIU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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