SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b94a90284982e056bad1af73a17e210a6a436ea0bf971ee578f0c9de3f50a43' 
  AND token = '/ML0qBQk9UHyH3pzkZD2Vi+rowwwGNvIREbnxIpqrAg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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