SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76249e68f4c827c72e5516f8c4af134172275e74ee1e493d221c83e78a25accc' 
  AND token = 'ITAdkKF1tI3SVu1DgpglhmQ9V6GZmpFJhzMEmNS8BBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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