SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ea4e9460c6150692c20d740b0619ef622f41787fecedfa10a1758aee3cb7135' 
  AND token = '8n5TFCtKERcgSXgPXg0Qsasv2ezhXjlwBDotSEVNNZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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