SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a210562899ed21775ceaff3e1a071b75e88a963545fe672a16adb6580e912238' 
  AND token = 'r2AYzzCzn7NTrJM8zVzK1DEllGRaDUHmzLYBR5Fr9jk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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