SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5458f3e294f9a1d23dce8824cf18b07bfbc346c7c8db6d3c314498e6a23953a8' 
  AND token = 'DpMVwDh4PMOyaxKKWBsCkeV/z3Dx8hB/UoOj/mO/bJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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