SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b58fbee7ed800a5c8aa4470bb8792fc6d0274e6af124cc20136e681a7faada6f' 
  AND token = '8wEjmHtEzX1lp9vqwdGIpHlQmfLzSIUOXeFxFyocimQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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