SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c30643876359eb012c752816f7c73da475d56f0d7cd6a18640cbac55d5ffbc8' 
  AND token = '4jM6XvU+0gCH52ZxRzkqaBqDukw4hWY6v+7uO9Ayn0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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