SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f4f220150d3e3d750cbd5fbf04e587f5073a491509e9fb868f5aa38f07cdaa5' 
  AND token = 'BSIyIHmAGc1qKXeByi0LRkwKa4WQiEOGpTG38n15Mlg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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