SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83838a5494f603ce3dc1f860edf28f3c5fb03a43625a80edfe8fdbe097433984' 
  AND token = 'PjNis/hM0VkPFtBoM1GkGaDnNY4KIccaHy8Nd2Z9O1c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}